For a summer commute from SF to Sacramento I'll bring a waxed cotton raincoat. After all, that's what all the people wear in that city that is famous for rain.
Or I can take a deep breath, admit to myself that I'm not a domain expert, and forge a relationship with someone who is.
This expert will use clues from the relationship to help me choose a garment. Maybe they find out I'm generally never in the elements for greater than 5 minutes. So they show me this dinky little windbreaker that is so light it can actually fit in my pocket. They explain how it isn't actually waterproof but it has a treatment that makes water bead off, and the ease of shaking it off and small size might be a decent tradeoff given my situation.
So now I'm carrying vastly less weight with a useful garment. I never would have chosen it on my own because my non-expert brain fixated on the word "waterproof" as if it were a boolean. Meanwhile, the domain expert measured the time it takes for water to penetrate the seams and found it plenty long enough to meet my needs.
> Anybody wants a nice, not-bulky, warm winter coat: buy it in Canada.
The current trailblazer is almost certainly Patagonia's micro puff jacket which uses a synthetic fill that AFAICT reaches the warmth-to-weight ratio of down. (Added potential benefit that the synthetic fill would continue to insulate if wet while down won't.)
Patagonia is a U.S. company, so you missed out on the latest greatest by choosing based on country conditions.
I'm being super finicky, and of course there are Canadian-made non-bulky winter jackets. But this thread started with someone wearing cotton in the summer heat. Such a person can just as easily buy a cotton hoody in Canada.